Note 5 - Debt Securities - Schedule of Unrealized Loss on Investments (Details) $ in Thousands	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Number of Securities in Loss Positions	311	157
Estimated Fair Value, Less than 12 Months	$ 220,777	$ 169,460
Unrealized Loss, Less than 12 Months	21,432	2,926
Estimated Fair Value, 12 Months or More	125,591	39,837
Unrealized Loss, 12 Months or More	30,159	837
Estimated Fair Value, Total	346,368	209,297
Unrealized Loss, Total	$ 51,591	$ 3,763
US Government Corporations and Agencies Securities [Member]
Number of Securities in Loss Positions	26	41
Estimated Fair Value, Less than 12 Months	$ 5,744	$ 6,630
Unrealized Loss, Less than 12 Months	100	23
Estimated Fair Value, 12 Months or More	10,544	21,061
Unrealized Loss, 12 Months or More	206	337
Estimated Fair Value, Total	16,288	27,691
Unrealized Loss, Total	$ 306	$ 360
Government Sponsored Agencies [Member]
Number of Securities in Loss Positions	58	19
Estimated Fair Value, Less than 12 Months	$ 26,975	$ 19,828
Unrealized Loss, Less than 12 Months	1,929	376
Estimated Fair Value, 12 Months or More	14,902	6,886
Unrealized Loss, 12 Months or More	2,075	212
Estimated Fair Value, Total	41,877	26,714
Unrealized Loss, Total	$ 4,004	$ 588
Nongovernment Sponsored Agencies [Member]
Number of Securities in Loss Positions	20	6
Estimated Fair Value, Less than 12 Months	$ 28,811	$ 4,345
Unrealized Loss, Less than 12 Months	1,596	61
Estimated Fair Value, 12 Months or More	8,882	7,591
Unrealized Loss, 12 Months or More	1,068	218
Estimated Fair Value, Total	37,693	11,936
Unrealized Loss, Total	$ 2,664	$ 279
Taxable State and Political Subdivisions General Obligations [Member]
Number of Securities in Loss Positions	56	41
Estimated Fair Value, Less than 12 Months	$ 18,116	$ 62,543
Unrealized Loss, Less than 12 Months	3,420	1,286
Estimated Fair Value, 12 Months or More	43,770	1,055
Unrealized Loss, 12 Months or More	15,731	37
Estimated Fair Value, Total	61,886	63,598
Unrealized Loss, Total	$ 19,151	$ 1,323
Taxable State and Political Subdivisions Sales Tax Revenues [Member]
Number of Securities in Loss Positions	4	2
Estimated Fair Value, Less than 12 Months	$ 1,842	$ 6,052
Unrealized Loss, Less than 12 Months	498	99
Estimated Fair Value, 12 Months or More	3,289	0
Unrealized Loss, 12 Months or More	1,268	0
Estimated Fair Value, Total	5,131	6,052
Unrealized Loss, Total	$ 1,766	$ 99
Taxable State and Political Subdivisions Lease Revenues [Member]
Number of Securities in Loss Positions		2
Estimated Fair Value, Less than 12 Months		$ 1,564
Unrealized Loss, Less than 12 Months		14
Estimated Fair Value, 12 Months or More		494
Unrealized Loss, 12 Months or More		12
Estimated Fair Value, Total		2,058
Unrealized Loss, Total		$ 26
Taxable State and Political Subdivisions Various Tax Revenues [Member]
Number of Securities in Loss Positions	7	5
Estimated Fair Value, Less than 12 Months	$ 3,253	$ 8,389
Unrealized Loss, Less than 12 Months	704	203
Estimated Fair Value, 12 Months or More	4,992	0
Unrealized Loss, 12 Months or More	1,758	0
Estimated Fair Value, Total	8,245	8,389
Unrealized Loss, Total	$ 2,462	$ 203
Taxable State and Political Subdivisions Income Tax Revenues [Member]
Number of Securities in Loss Positions		1
Estimated Fair Value, Less than 12 Months		$ 721
Unrealized Loss, Less than 12 Months		3
Estimated Fair Value, 12 Months or More		0
Unrealized Loss, 12 Months or More		0
Estimated Fair Value, Total		721
Unrealized Loss, Total		$ 3
Taxable State and Political Subdivisions Utility Revenues [Member]
Number of Securities in Loss Positions	3	3
Estimated Fair Value, Less than 12 Months	$ 1,542	$ 5,175
Unrealized Loss, Less than 12 Months	459	130
Estimated Fair Value, 12 Months or More	2,466	0
Unrealized Loss, 12 Months or More	834	0
Estimated Fair Value, Total	4,008	5,175
Unrealized Loss, Total	$ 1,293	$ 130
Taxable State and Political Subdivisions Other Revenues [Member]
Number of Securities in Loss Positions	16	1
Estimated Fair Value, Less than 12 Months	$ 12,588	$ 744
Unrealized Loss, Less than 12 Months	2,792	9
Estimated Fair Value, 12 Months or More	1,148	0
Unrealized Loss, 12 Months or More	328	0
Estimated Fair Value, Total	13,736	744
Unrealized Loss, Total	$ 3,120	$ 9
Corporate Debt Securities [Member]
Number of Securities in Loss Positions	20	10
Estimated Fair Value, Less than 12 Months	$ 11,579	$ 10,534
Unrealized Loss, Less than 12 Months	773	314
Estimated Fair Value, 12 Months or More	10,071	990
Unrealized Loss, 12 Months or More	774	10
Estimated Fair Value, Total	21,650	11,524
Unrealized Loss, Total	$ 1,547	$ 324
Asset-Backed Securities [Member]
Number of Securities in Loss Positions	15	8
Estimated Fair Value, Less than 12 Months	$ 21,781	$ 10,522
Unrealized Loss, Less than 12 Months	283	86
Estimated Fair Value, 12 Months or More	620	751
Unrealized Loss, 12 Months or More	12	1
Estimated Fair Value, Total	22,401	11,273
Unrealized Loss, Total	$ 295	$ 87
Tax Exempt State and Political Subdivisions General Obligations [Member]
Number of Securities in Loss Positions	58	13
Estimated Fair Value, Less than 12 Months	$ 59,699	$ 25,555
Unrealized Loss, Less than 12 Months	4,542	261
Estimated Fair Value, 12 Months or More	21,189	853
Unrealized Loss, 12 Months or More	5,082	9
Estimated Fair Value, Total	80,888	26,408
Unrealized Loss, Total	$ 9,624	$ 270
Tax Exempt State and Political Subdivisions Water And Sewer Revenues [Member]
Number of Securities in Loss Positions	14	1
Estimated Fair Value, Less than 12 Months	$ 12,298	$ 904
Unrealized Loss, Less than 12 Months	1,457	15
Estimated Fair Value, 12 Months or More	682	0
Unrealized Loss, 12 Months or More	225	0
Estimated Fair Value, Total	12,980	904
Unrealized Loss, Total	$ 1,682	$ 15
Tax Exempt State and Political Subdivisions Lease Revenues [Member]
Number of Securities in Loss Positions	3	1
Estimated Fair Value, Less than 12 Months	$ 3,762	$ 2,396
Unrealized Loss, Less than 12 Months	138	31
Estimated Fair Value, 12 Months or More	1,874	0
Unrealized Loss, 12 Months or More	521	0
Estimated Fair Value, Total	5,636	2,396
Unrealized Loss, Total	$ 659	$ 31
Tax Exempt State and Political Subdivisions Various Tax Revenues [Member]
Number of Securities in Loss Positions	4
Estimated Fair Value, Less than 12 Months	$ 6,312
Unrealized Loss, Less than 12 Months	1,417
Estimated Fair Value, 12 Months or More	128
Unrealized Loss, 12 Months or More	28
Estimated Fair Value, Total	6,440
Unrealized Loss, Total	$ 1,445
Tax Exempt State and Political Subdivisions Other Revenues [Member]
Number of Securities in Loss Positions	7	3
Estimated Fair Value, Less than 12 Months	$ 6,475	$ 3,558
Unrealized Loss, Less than 12 Months	1,324	15
Estimated Fair Value, 12 Months or More	1,034	156
Unrealized Loss, 12 Months or More	249	1
Estimated Fair Value, Total	7,509	3,714
Unrealized Loss, Total	$ 1,573	$ 16